diff --git a/evals/postmortem/live_ab/batch_failure_notice.py b/evals/postmortem/live_ab/batch_failure_notice.py
index d713e8f3bf..1e17dc895a 100644
--- a/evals/postmortem/live_ab/batch_failure_notice.py
+++ b/evals/postmortem/live_ab/batch_failure_notice.py
@@ -27,7 +27,9 @@ dd._Batch.run_child = fake_run_child
 # Background dispatch requires an async-capable session; emulate a CLI session key.
 import tools.async_delegation as ad
 t0 = time.time()
-out = dt.delegate_task(tasks=[{"goal": "fail fast on a simulated 401 error"}, {"goal": "slow successful worker number one"}, {"goal": "slow successful worker number two"}], background=True, parent_agent=parent)
+out = dt.delegate_task(# Grouped: siblings share ONE final result, so a dead sibling would otherwise wait for the slowest. (Ungrouped tasks are
+# their own async unit since the per-group split landed on main and already report as they finish.)
+tasks=[{"goal": "fail fast on a simulated 401 error", "group": "g"}, {"goal": "slow successful worker number one", "group": "g"}, {"goal": "slow successful worker number two", "group": "g"}], background=True, parent_agent=parent)
 print("dispatch:", json.dumps(json.loads(out))[:160])
 seen = []
 deadline = time.time() + 30
diff --git a/evals/postmortem/review_probes/notice_delivery_probe.py b/evals/postmortem/review_probes/notice_delivery_probe.py
index 8869b13f96..70a6a8f547 100644
--- a/evals/postmortem/review_probes/notice_delivery_probe.py
+++ b/evals/postmortem/review_probes/notice_delivery_probe.py
@@ -35,9 +35,11 @@ class Sink(GatewayNotificationsMixin):
         return True
 
 def batch_run(did, gates):
-    tasks=[{'goal':f'worker task {i}'} for i in range(3)]
+    tasks=[{'goal':f'worker task {i}','group':'g'} for i in range(3)]  # grouped: one shared final, so the early notice matters
     children=[(i,t,SimpleNamespace()) for i,t in enumerate(tasks)]
     b=dd._Batch(tasks,children,SimpleNamespace(quiet_mode=True),{'model':'offline'},None,'leaf',3,did,[],[], '', '',None,None,time.monotonic())
+    # Since the per-group split on main, a detached unit carries its registry id; the notice keys on it.
+    if hasattr(b,'unit_id'): b.unit_id=did; b.group='g'
     def child(i,t,c):
         assert gates[i].wait(15)
         return {'task_index':i,'status':'error' if i<2 else 'completed','error':'offline failure' if i<2 else None,'summary':None if i<2 else 'FINISHED_SUCCESS','duration_seconds':0.1}